Cardiac recording apparatus



Aug. 8, 1939. H. WEISS CARDIAC RECORDING APPARATUS 3 Sheets-Sheet 1 INVENTGR YAWMQ Wm M ATTORNEY war}; 1);

Filed Oct. 28, 1936 Aug. 8, 1939.

H. WEISS CARDIAC RECORDING APPARATUS Filed Oct. 28, 1936 3 Sheets-Sheet 2 \N mw INVENTORK J/ar'cy Mei.

Fla 8 s 1 mm W M ATTORNEY Aug. 8, 1939.

H. WEISS CARDIAC RECORDING APPARATUS Filed Oct. 28, 1936 3 Sheets-Sheet 5 Q AR m & N A N V w Q 7 INVENTOR Warr' Z L JJ m L 1 ATTORNEY Patented Aug. 8, 1939 UNITED STATES PATENT OFFICE A 8 Claims.

This invention relates to an automatic and graphic blood pressure recording device intended for use primarily in clinical and experimental cardiac work or in any situation where a constant and automatic blood pressure record for a predetermined period of time is of value.

One of the objects of the invention is to provide an automatic and graphic blood pressure recording device which shall be useful in various environments, during sleep, at rest, or during various stages of activity; which shall be capable of automatic blood pressure recording for any desired period of time, or at predetermined intervals of time. This will permit the automatic and graphic determination of blood pressure changes, with changes in the psychic, mental or physical state of the person being tested.

A further object of the invention is to provide a means whereby the application and release of pressure on the artery of a patient may be recorded in the form of a curve similar to a sine curve on a photographic record strip and simultaneously therewith and as a part of the same curve, the arterial sounds occurring and disappearing during the application of and release of pressure will also be recorded. The advantages of such an arrangement will be at once apparent to those skilled in this art.

In the accompanying drawings, wherein several illustrative embodiments of the invention are shown, Fig. 1 is a diagrammatic view of a practical structure capable of performing the functions desired to be achieved by the invention; Fig. 2 is a diagrammatic view showing the pres-- sure means used in connection with the structure of Fig. 1; Fig. 3 is a diagrammatic view of a manometer and the connections therefrom to the structure of Fig. 1; Fig. 4 shows a modified structure; and Fig. 5 is a diagrammatic view showing the manner in which the image of a galvanometer string shadow may be reflected by a mirror to a recording camera.

In the drawings is shown a string galvanometer in which l indicates an electro-magnet, wound in the ordinary manner over a soft iron core and energized by means of the battery I l or any other suitable source of current. Said electro-magnet III provides a magnetic'field within which the string I 2 is vibrated. In addition to having a vibratory movement, the string is capable of bodily shifting movement, that is, back and forth within the magnetic field. To attain this bodily movement, the string is attached at its ends to a movable housing l3 which is moved by operation of the pump [4 shown in Fig. 2 or hand operated as will be hereinafter set forth. As the housing Ills moved by operation of said pump or by a hand bulb, it moves the string I! back and forth through the magnetic field of magnet ill from one side to the other, thus moving the string through said fleld from right to left and then back from left to right.

The housing l3 includes a pair of spaced sleeves or tubes I5 and I6 rigidly connected by end members H. The string I2 is connected between the two sleeves and passes through the field of the magnet, the poles of the magnet being split to provide a slit [9 through which a light beam may pass to direct an image of the string on a photographic record strip. 16

I The housing i3 is movably supported upon a pair of spaced-apart hollow fixed forks 20, 2|. Each fork has a pair of tubular extensions entering into the sleeves i3 as clearly shown in Fig. 1 of the drawings. Connected to the forked member 20 by means of a flexible tube 23 or the like, is the pump 14 (Fig. 2) which is actuated by hand or by means of an electric motor or other source of power. The pump is so designed that the displacement of its piston 24 will govern the quantity of air flowing through tube 23 and into fork 20. The stroke of the piston can be regulated in any well known manner as, for example, attaching the end of the piston rod to a selected point on an eccentric attached to the motor drive shaft.

The limits of pressure between which the device will operate can also be controlled by shifting the position of the pump cylinder with respect to its piston, this being done by having the cylinder adjustably mounted on a base on which it can be moved and fixed at any selected position. In this way two adjustments are obtainable, one, an adjustment of pressure between any two pressures desired and, two, another adjustment of pressure making that fluctuation within any range desired. Thus, if an aplitude of 100 millimeters of mercury is desired between 20 millimeters and 120 millimeters, that can be obtained; or if the same amplitude is desired between and 150, that can also be obtained. Also the amplitude itself can be varied by control of the operator as heretofore described.

A bypass 31 extending from tube 36 (hereinafter described) goes to and through a stop-cock 38 to a hand bulb capable of inflating, and by releasing a screw valve upon it, is capable of deflating the air pressure previously described above. This hand bulb functions as a further adjustment to set the machine at any point desired and can also function when manual inflation and deflation of the air pressure system would be desirable.

As the air is pumped in and out of fork 20 and into tubes I5 and I6, which are centrally closed by the diaphragms 26, the entire frame I3 carrying the string I! will be moved thus causing string l2 to be moved back and forth through the magnetic field of magnet 10.

The fork 2! is connected by flexible tube 28 or the like, to a mercury manometer 28 identical with that used in the conventional measurement of blood pressure. Air contained in the portions of the tubes l5 and I6 to the left of diaphragms 26 will, upon movement of the frame l3 to the left and right cause the mercury in the manometer to raise and lower in the conventional manner. A bypass and stop-cock 39 are provided in the flexible tube 26 in order to permit adjustment of the string l2 at its zero point when the whole system is at atmospheric pressure. The rate of movement of the frame l3 can, of course, be controlled by the speed of the pump-operating motor. Also any known form of timing device can be used to turn the motor on and off to thereby take blood pressure at specified intervals within the control of the operator.

At one side of the magnetic field of the magnet I0 is a source of light. This is conventional in string galvanometers, such as shown for example in the patent to Kruse, No. 1,882,402, dated October 11, 1932. On the opposite side is a photographic recording camera such as is also shown in the above-mentioned patent, utilizing a continuously moving film strip on which in the present invention, movements of the string l2 as it passes to and fro on the movement of the frame l3, will be recorded, giving a picture on the film resembling that of a sine curve. At its upper and lower ends, the string I2 is provided with contacts 21 and 28 connected to the wires 29 and 30 extending from the secondary 3i of an induction coil 32. The primary of this induction coil is connected to a small microphone diagrammatically indicated at 33. The microphone is activated in the ordinary way from a low-voltage, low-amperage cell. The position of the secondary with respect to the primary is adjustable and this, combined with the variable resistance 34, controls the sensitivity of the string and the amplitude of its movement.

In practice, the microphone 33 is adapted to be attached to the anti-brachial space of the arm over-the artery and it will pick up the sounds produced as the arm is compressed and released in the ordinary fashion by a blood pressure cuff and record these sounds by vibrations of the string l2v which is moving back and forth across the field of magnet in. The blood-pressure cuff is inflated and deflated by action of the pump l4 (or by a hand bulb when desired) and is connected to the pump by the bypass 35 which connects to the cuff by means of the flexible tube 36 or the like. With the apparatus disclosed, a record is mad not only of the pressure changes from the pump, as indicated by the bodily movement of the string through the magnetic field, but also the vibratory movement of the string as it is vibrated by microphonic action according to the arterial sounds picked up by the microphone as the arm is compressed and released. The device may be worn while a patient is working, sleeping or engaging in exercise and a complete record of the effect of anyexertion may be recorded on the film.

I have shown the string movable with respect to the magnetic field, but it will be obvious to those skilled in the art that both the magnet and string might be moved together as a unit to secure results similar to those set forth, but with a somewhat more complex apparatus. I also contem plate, as a substitute for the bodily -movable string, the utilization of a mercury manometer, such as diagrammatically illustrated at 28", but provided with contacts spaced at every five millimeters. With such an arrangement, as the mercury rises and falls in the manometer with changes in pressure from the pump, these contacts can be recorded on the film. This is another way of definitely recording on the film the changes in pressure from the pump. I also contemplate keeping the relative position of the string, the magnetic field and the source of light fixed, by mounting the camera in a housing similar to that described and to move the camera from side to side and by doing so, obtaining a graphic image of the string similar to that described when the string is moved or where the string and magnetic field are moved as a unit.

I have herein stated that the image of the string falls directly upon the lens of the photographic recording camera which transmits the image upon the travelling film strip. It is old in this art to project by means of a fixed mirror, the image of the string to the lens of the camera. When such a mirror arrangement is utilized, it is possible to use a fixed string rather than the bodily movable string herein described, and oscillate or swing the mirror backward and forward, so that the effect of a bodily movable string on the strip is obtained without actual movement of the string itself. In such case, the mirror can be mounted on a frame similar to that shown at 13 or so connected to said frame as to be oscillated thereby as the frame is moved back and forth by the action of the pump. A structure of this character is diagrammatically illustrated in Fig. 5. There a source of light is indicated at 50 from which a fiat beam of light is directed through the aperture or slit in the magnetic field of magnet l0, throwing the shadow of the string I2 ontothe mirror 5| or to a mirror placed as shown at 52. The mirror is mounted on a vertical pivot indicated at Sla'and is oscillated by torsion corresponding to changes in the blood pressure. Suitable operating means interposed between tube 23 and the mirror can be employed to oscillate the mirror on its pivot 5la in response to action of pump I. The image of the string shadow in mirror 5| is reflected directly back to the camera indicated at 53 which is located on the same side of the magnetic field as the source of light 50. If a mirror is placed as shown at 52 the image of the string shadow can be directed sidewise to the camera placed as at 54. It will be apparent that by suitable mirror and camera positioning reflection of the string shadow to a camera in any selected position can be had.

It is proposed as a modification and simplification of the string galvanometer apparatus described above for automatic and graphic blood pressure recording, to use in place of the string and the magnetic field a crystal or magnetic oscillometer fixed in the housing heretofore described and replacing the string and magnetic field in the manner shown in Fig. 4. The housing and its accessories remain the same. At a central point between the sleeves I3 is rigidly fixed a crystal oscillometer 10, which, asconstructed at the present time, is hermetically sealed in oil.

The

crystal oscillometer employed may be of quartz, magnesium sulphate or of other crystals. The type of crystal employed is immaterial due to the property of all crystals to distort when a current is passed through them. Easily available crystal oscillometers are those of quartz and magnesium sulphate. An example of such an oscillometer is The Brush oscilloscope manufactured by The Brush Development Company of Cleveland, Ohio. A window 4| in the casing containing the oscillometer permits the light reflected from a mirror 42 attached to the crystal to be reflected on to a photographic strip as previously described. This crystal is activated and oscillated by connections 29 and 30 extending from the microphone 33 and its auxiliary apparatus as heretofore described. The movement of the housing and oscillometer will produce upon a photographic strip a curve similar to a sine curve while the oscillations of the mirror activated by the crystal which in turn is activated by the microphone and its accessories will produce deflections from this curve or show the absence of deflections as the blood pressure, and with it the position of the housing and the oscillometer, are automatically changing. A similar result can be obtained by using a fixed oscillometer with a moving camera like that previously described.

It will be obvious that the apparatus and the various modifications herein described are susceptible to many uses and many modifications coming within the scope of the annexed claims. It is also obvious that the apparatus described will also automatically record pulse rates over any fixed period of time or at such intervals and over such periods as may be desired.

What I claim is:

1. In an apparatus of the character described, a string galvanometer including means for producing a magnetic fleld within which the string is disposed, means for bodily moving the string in said fleld, means for recording such movements of the string as well as vibratory movements thereof, and pressure-creating means connected to a blood-pressure cuff and causing the bodily movements of the string co-incidentally with the application and release of pressure on the arm of the wearer of the cuff.

2. In an apparatus of the character described, a string galvanometer including means for producing a magnetic fleld within which the string is disposed, means for supporting the string within said magnetic fleld, a pump having its output connected to a blood-pressure cult and also to the string supporting means whereby the application and release of pressure in the suit will move the string bodily back and forth within the magnetic field, means for recording such bodily movements of the string and means for simultaneusly recording vibratory movements of the string while it is being bodily moved under action of the pump.

3. In a device of the character described, a constant blood-pressure recording device including means for producing a magnetic field, a galvanometer string and means for supporting the same in said fleld to permit of movement back and forth within the fleld, a photographic recording camera through which a sensitive strip is fed, means for directing an image of the string onto the sensitive strip, pressure-creating means for shifting the string back and forth within the magnetic field, and means for transmitting arterial sounds to the string while said string is being moved.

4. In a device of the character described, a galvanometer string, air pressure means, means for bodily moving said string by operation of said air pressure means, means for recording said movements of said string, and means for recording arterial sounds by vibrations of said string while it is being bodily moved.

5. In an apparatus of the character described, a recording element regularly movable within a predetermined path, pressure-applying means for automatically alternately and regularly moving said element within said path, a blood-pressure cult to which said pressure-applying means is connected to apply and release pressure therein co-incidentally with the application and release of pressure to said movable element, recording means by which the alternate and regular movement of said element is recorded, and means by which said movable element indicates through said recording means arterial sounds occurring during the application and release of pressure on the blood-pressure cufi.

6. In an apparatus of the character described, a recording element movable within a predetermined path, a pump having its output connected to a blood-pressure cult and also to said recording element whereby the application and release of pressure in the cuff caused by pump operation will simultaneously move the recording element within its predetermined path of movement, a single means for recording such predetermined movements of the recording element and for recording supplementary movements of the element occurring while said element is being moved under the action of the pump.

7. In an apparatus of the character described, a recording element, air pressure means, means for normally and regularly moving said element by operation of the air pressure means, means for recording such normal and regular movements of the recording element, and means for recording arterial sounds by supplemental movements of the recording element caused by the sounds while said element is being normally and regularly moved.

8. In an apparatus of the character described, a blood-pressure cuff, automatic means ior alternately applying and releasing pressure within the cuff at definitely established predetermined intervals, a movable recording means for recording the alternate regular application and release of pressure, the movements of said recording means being controlled-by the pressure-applying means, and-means for causing said recording meanstoalsorecordarterialsoundsduringthc application and release or said pressure. 7

HARRYWEIBS. 

